I supplied the verse below. but first let me ask you, what is required for baptism?
isn't repentance and faith?
Yes, that and submersion in water.
Which leads me to the question, “How can a child repent or have faith?”
Most children believe what their parents tell them, they do not have any real foundation for what one calls “faith” in Jesus until they are old enough to actually understand what it means.
As for whether or not they “sin at all” all humans are born with the stain of original sin upon them. They need not sin at all to be sinners due to this doctrine.
Then there is the argument of infants and those who will never even hear of Christ’s message they surely are hell bound.
The verse you cite does not state that children get an auto pass into heaven.
Matt 18 :3-4 .. and said, “Assuredly, I say to you, unless you are converted and become as little children, you will by no means enter the kingdom of heaven. Therefore whoever humbles himself as this little child is the greatest in the kingdom of heaven.
The verse above pertains to the ignorance of a child, a child does not question, a child is not worldly, a child can be easily led.
You must be as “humble” as a child to enter heaven.
It does not say “Children enter heaven”
The verses below state what is necessary for salvation.
John14:6 Jesus said to him, “I am the way, the truth, and the life. No one comes to the Father except through me
Matt13:23 But he who received seed on the good ground is he who hears the word
and understands it, who indeed bears fruit and produces: some a hundredfold, some sixty, some thirty.”
John3:5 5 Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.